Spark plug



0a. e, 1925. i 1,556,603

w. MCELROY SPARK PLUG Filed May' 24 1922 f4.9. i a

.enum

INVENTOR.

BY a4.

ATT NEY.

Patented Oct. 6, 1925.

' UNITED STATES 1,556,003 PATENT oFF-ICE.

WILLIAM MCELROY, 0F BROOKLYN, NEW YORK, ASSIGNOR OF ONE-THIRD T0 WIL- LIAM MGELROY, JR., ONE-THIRD TO MITCHELL MCELROY, AND ONE-THIRD T0 WIL- LIAM WOLF, ALL OF BROOKLYN, NEW YORK.

SPARK rLUG.

Application file d May 24, 1922.

To all whom t may concern.'

Be it known that I, WILLIAM MCELROY, a citizen of the United States, residing at New York city, borough of Brooklyn, county of Kings, and State of New York, have invented a certain new and useful Spark Plug, of which the following is a specification.

This invention is a spark plug for internal combustion engines and the object of the invention is to provide a plug which may be used with engines' of diiferent kinds or makes with equal efiiciency. It is well known that in some engines some of the heads are deeper than in others. That is to say, some engines require longer spark plugs than others. It is accordingly the practice to build spark plugs of different lengths so that for the relatively shallow cylinder heads, a correspondingly short plug is employed, while for the deeper heads longer plugs are used. n

The present invention is a plug, the length of which may be readily varied. That is to say, the plug is adjustable as to length to adapt it for use with cylinder heads of different depths.

In practically carrying out the invention, the shell of the plug which is threaded to screw into a spark plug opening of the cylinder head is made somewhat longer than usual. The insulating element of the plug is provided with an enlarged cylindrical portion which is adapted to be clamped into position within the shell by means of a j amb l nut.

In carrying out the present invention however, a plurality of spacing rings are employed which are adapted to cooperate with the .enlarged portion of the insulating element for the purpose of making the adjustments referred to. I

From a more specific standpoint, the spacing rings referred to may be apportioned above and below the enlarged portion of the insulating element, so as to raise or lower the insulating element with reference to the shell. The insulating element carries the usual central electrode and also has associated therewith two other supplementary electrodes to which the current from the central electrode jumps to produce a spark prior to the jumping of such current from the supplementary electrodes to the shell and thence to ground. The employment of Serial No. 568,329..

the supplementary electrodes enables the adjustment of the insulating element without varying the gap and thereby assures maximum efficiency of the plug at all times irrespective of adustment.

Features of the invention, other than those specified, will be apparent from the hereinafter detailed ldescription and claim, when read in conjunction with the accompanying drawings.

The accompanying drawings illustrate one practical embodiment of the invention, but the construction therein shown is to be understood as illustrative, only, and not as defining the limits of the invention.

Figure l is a central section of a plug embodying the present invention; and,

Figure 2 is a perspective view of substantially the lower half of the insulating element.

Referring to the drawings, l designates the shell of the plug, the upper portion 2 of which is preferably made polygonal to receive a wrench and the lower portion 3 of which is reduced and threaded to screw into the spark plug hole of an engine cylinder. The shell 1 is somewhat longer than usual and is provided with an interior shoulder 4, forming a seat. The interior of the plug above the seat 4 is cylindrical and of greater diameter than that portion of the interior of the shell below said seat. The upper portion of the shell is interi'orly threaded as at 5 to receive an annular jamb nut 6.

7 designates the insulating element of the plug which may be constructed of porcelain or any other suitable material. It is provided intermediate its ends with an enlarged cylindrical portion 8 of such size as to enter the upper portion of the plug, but so large that it will not pass the shoulder 4. A central metallic electrode 9 extends longitudinally through the insulating element, and projects above the top thereof, so as to receive a binding nut l0 for securing an ignition lead to the plug. The lower end of the central electrode 9 projectsl slightly beyond the lower end of the insulating element as shown in the drawings.

Extending in parallel relation to the electrode 9 and spaced at diametrically opposite sides therefrom are two supplementary electrodes 11. These electrodes are housed within cylindrical passages 12, which extend upwardly from the bottom of the element 7 to cut out portions 13 and the upper end of each supplementary electrode 11 is slotted, and the halves 11L thereof bent outwardly in opposite directions, after the manner of a cotter key, as best shown in Figure 2, so as to occupy the cut outs 13 and preclude the supplementary electrodes from dropping out of the cylinder channels 12 in which they are housed. A slot 14 extends diametrically from each cylindrical channel 12 to the periphery of the insulating element as clearly shown in Figure 2.

Slots 14 are adapted to provide for the passage of electric current from the supplementary electrodes 11 to an iii-turned flange 15 at the lower end of the'th'readed portion 3 of the shell 1. In other words, the current is adapted to jump from the central electrode 9 to either one or both of the supplementary electrodes 11 and produce atV this point or points the spark for firing the eX- plosive charge, whereupon the current is adapted to thereafter jump from the supplementary electrodes through either one or both of the slots 14 to the flange 15, whence such current passes to ground.

As shown in the drawings, the supplementary electrodes are relatively long as are also the slots 14:, so as to provide a relatively wide range of longitudinal adjustment of the insulating element 4;, which carries said electrodes. This adjustment is accomplished vthrough the proper positioning of a 'plurality of spacer' rings designated` in thev drawings by the reference character 16. Any number of these rings may be employed and they may be constructed of any suitable material but four are shown in the drawings. Three are shown as positioned intermediate the shoulder 4 and the enlargement 8 of the porcelain, while it is shown between the enlargement 8 and the lower end of the jamb nut 6. As shown the adjustment is such as to be particularly adapted for use with motors having relatively v shallow cylinder heads. If the spark plug is to be used with an engine having a relatively deep cylinder head, the jamb nut 6 is removed and the rings 16 shifted, for example by taking one or more of the rings 16 from below the enlargement 8 and positioning it above such enlargement, so that when the parts are again assembled and the nut 6 screwed down tightly, the new adjustment will be` such as tov effect a lowering of the porcelain, so that n the lower end thereof will project further in the direction of the interior of the engine cylinder. By properly apportioning the rings 16 above and below the enlargement 8 of the insulating element, the plug may be adjusted for proper operation with any cylinder in a simple and expeditious manner.

- rIhe arrangement of the supplementary electrodes is such, moreover, that proper sparking will result irrespective of the degree of adjustment. It will be therefore understood that the sparking between the supplementary electrodes and flanges 15 will have an intensifying effect on the primary spark between the central electrode and the supplementary electrodes and produce a hotter spark at this point.

In practically carrying out the invention, the adjusted rings 16 may be of any suitable material, but are preferably such that they will make a tight joint and preclude leakage of compression, although, if desired, gaskets may be used in conjunction therewith.

In the foregoing description, I have set forth in detail the preferred embodiment of my invention. I am aware however that slight details of construction may be changed such as by the substitution of equivalents without departing from the spirit of this invention. Moreover, instead of employing two supplementary electrodes, one may be employed without departing from the invention. Accordingly, the invention is to .be understood as not restricted to the specific showing of the drawings, but are as broadly7 novel as is commensurate with theappended claim. I

Having thus fully described the invention,

what I claim as new and desire to secure by Letters Patent is:

A spark plug embodying a shell, an insulating element, means for supporting the insulating element for adjustment longitudinally of the shell, a central electrode carried by the insulating element, a supplementary electrode also carried by the insulating element and extending longitudinally thereof in spaced relation to the central electrode and to the shell, said supplementary electrode being housed within a channel in the insulating element and a channel having an opening to the periphery of the insulating element, whereby electric current passed through the plug may jump the gap from the central electrode to the supplementary electrode, and from the supplementary electrode to the shell in any of the positions of adjustment ofthe insulating elementrela'- tivei to the shell.

WILLIAM MCELROY.

y 115 In testimony whereofvI havey signed the 

